In view of a material rise of cost of organic fossile fuels their partial replacement with secondary energy sources without hampering the effectiveness of combination is a very actual problem in all industrially developed countries.
Known in the art are burner devices for burning different kinds of solid, liquid and gaseous fuels exhibiting different thermophysical properties, comprising concentrical annular passages for feeding air and fuels (cf. the books by Speysher V. A., Gorbanenko A. D. "Improvement of the Efficiency of the Use of Gas and Fuel Oil in Energy Production Plants", M., Energia Publ., 1974, p. 208; Maslov V. I., "Operation of Boiler Units in Ferrous Metal Production", M., Energia Publ., 1965, p. 296; Vnukov A. K., Reliability and Effectiveness of Boilers for Gas and Fuel Oil, M., L., Energia Publ., 1966, p. 368).
At present some designs of burners make it possible to ensure a highly efficient burning of different types of fuel in a concurrent and separate manner of fuel feeding so as to facilitate the fuel consumption, and the formation of nitrogen oxides may be substantially lowered by adding low-calorie gases.
Known in the art is a burner for burning gases of different calorific capacity, comprising concentrically arranged annular passages for feeding blast-furnace gas (a peripheral passage), air and a high-calorie gas successively to the center (cf. German Pat. No. 1,060,082, Cl. 24 C, 10). In such burner, the outlet zone of the peripheral passage is provided with a converging nozzle, the diameter of the outlet section of the converging nozzle is greater than the diameter of the air passage therein, and the outlet end faces of all passages are in one end the same plane.
The disadvantage of such burner consists in that the intensity of formation of a mixture of blast-furnace gas with air is inadequate, and an intense heating of the outlet zone of the peripheral blast-furnace gas passage with radiated heat when this passage is disconnected lowers the reliability of operation.
Known in the art is a burner comprising an annular passage with an axial-and-vane type vortex chamber in the outlet portion thereof and passages for air and coal dust supply arranged in and concentrically with the annular passage (cf. USSR Inventor's Certificate No. 191,734, Cl. F 23 D 17/00, 1967). The cylindrical outlet portion of the peripheral blast-furnace gas passage in such burner is greater than the diameter of the intermediate air passage accommodating gas supply tubes for feeding natural and coke gases.
This combination burner is deficient in an inadequate efficiency of mixture formation and an intense heating of the outlet members of the blast-furnace gas passage upon its disconnection.
The above disadvantages are caused by a concurrent development of annular flows of blast-furnace gas and air with substantially equal velocities and by the absence of cooling of the peripheral portion of the burner when the blast-furnace gas is disconnected. Angle coefficients for radiation of the fuel spray incident upon non-cooled members are sufficient for their overheating with actual heat fluxes from fuel sprays of the burner proper and from adjacent burners owing to a difference in diameters of the blast-furnace gas and air passages.
Known in the art is a burner comprising coaxially arranged passages: a passage for secondary air and high-calorie gas and primary air passages coaxial therewith. The outer cylindrical wall of the high-calorie gas passage is the inner wall for the secondary air passage and the inner cylindrical wall is the outer wall for an air mixture passage (cf. Talibdzhanov Z. S., Golovanov A. V., Reversible Dust, Gas and Fuel Oil Burners with Adjustable Fuel Spray, in the paper, Gas Applications in the National Economy, M., VNIIEGazprom, 1975, pp. 3-12).
This burner enables an efficient burning of a solid constant composition fuel in a concurrent and separate manner with fuel gases.
The disadvantage of this burner resides in hampered combustion performance in case the composition of solid fuel substantially deviates from the design composition.
In addition, after a continuous burning of abrasive dust of a solid fuel the wall separating the passages for air mixture and high-calorie gases is rapidly worn to result in an explosion hazardous situation.